Many here have seen my prior posted struggles with USB3, Pi4, and wireless. Finally, after a month+ of pulling my hair out trying to get my config to work right, I think I finally understand what is going wrong. Hopefully this note will help others avoid my experience. The long and short is that the Pi4's USB3 ports are jamming 2.4Ghz Wifi. What many suggest is "power issues" turns out to be USB3 RF interference. This ONLY occurs for USB3 + 2.4Ghz connections. The symptom is that the 2.4Ghz wireless network will either not be visible, or will drop back to hotspot as soon as USB3 is detected (boot time or at cable reconfig). Pi4 is an almost perfect 2.4Ghz wireless self-jamming device due to having its USB3 ports and HDMI ports in close proximity to the wifi antenna (top of board near GPIO pins 1-6). Poor shielding (cables and connectors) can magnifiy the issue, but even good cables won't eliminate the problem. Some particular Pi4 casings can help (better grounding), others will hurt. Cable lengths and device distances also factor in the RF interference @ 2.4Ghz. Too many variables! Many have responded to my prior posts that their Pi4 setups work fine. I believe those Pi4s that ARE working are not using USB3 + 2.4Ghz wireless networking (or fortune has smiled on them greatly). That said, the Pi4 + USB3 CAN work great under certain circumstances:
- Pi4 + USB3 + 5Ghz wireless should be fine.
- Pi4 + USB3 + hard wired (cable) Ethernet is ok
- Pi4 + USB3 + blind hotspot is ok (i.e. NOT mapped back to a 2.4Ghz "infrastructure" internet source).
- Very curiously, I can most often get stable USB3 with 2.4Ghz AFTER booting with USB2 (i.e. cableup USB2 port, boot, then move cable to USB3 after ~minute).
- Pi4 + USB2 + 2.4Ghz wireless (+ Powered USB3 hub in downgrade USB2 mode) works fine.
What will NOT consistently boot is Pi4 + USB3 + 2.4Ghz wireless. I recently found the Intel white paper on this general issue from years ago. Fits my symptoms exactly. Here's the link: www.intel.com/content/www/us/en/products...erference-paper.html
USB3 RF interference @2.4Ghz is the problem. RF interference @2.4Ghz also occurs for HDMI, Bluetooth, and even a particular screen resolution! Looking back now at many forum posts (here and in the Raspberry Pi forum), where Pi4 + USB3 + 2.4Ghz odd networking issues occur, these may have a (known or unknown) underlying RF interference factor.
So, Pi4 + USB3 is great (more memory, faster CPU, USB3 allows 10X read/write performance gain and SSD longevity benefits over SD). Just be wary of USB3, bluetooth, and HDMI with 2.4Ghz wireless. I tried multiple different twisted/shielded USB3 cables and carefully mapped out all power (to eliminate this as a possible issue). The Pi4 design itself is part of the problem...not their fault...just hard to have HDMI, USB3, and wireless using 2.4Ghz in close proximity. In the end, for my use, I will add an Ethernet cable to retain a USB3/network speed advantage. If you're trying to stay wireless with USB3, be prepared to need 5Ghz, or stay with blind hotspot mode(which requires off-line platesolving and image transfers via cable or sneaker-net). Hope this helps someone. Cheers all....
Interesting! That could also explain what I am experiencing and could never explain: My 5GHz Wifi will never connect to my home Wifi, UNLESS I have a 2.4 GHz dongle attached to the USB port. Only then will the 5GHz network connect and after that I have no more problem with it.
I thought that was OS related. Never thought it could be the antenna placement, but I guess it's possible.
Thanks for digging up that info!
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My RPi4 just arrived today. Revision 1.2. Yup, there are some serious WiFi issues. My 5G WiFi kept dropping while trying to install the AstroPi3 packages from @rlancaste. Only use connection was keyboard and mouse to USB2. I read a thread about QWHD resolution HDMI causing the problem, which I was running at the time, but changing the resolution to 1080p did not help the cause. I grabbed a network cable and made a direct connection to my router (satellite) to finish the process. This makes me nervous about sustained use in the field, or even from my backyard via WiFi.
HDMI is included in the RF interference category with USB3 against wireless, but ONLY for 2.4Ghz. There are successful Pi4 users of 5Ghz wireless on this forum. Again, it's only 2.4Ghz that's impacted by HDMI and/or USB3. USB2 is ok. If you can't get 5Ghz to work reliably, then you might want to second guess whether your power supply is delivering amps sufficiently...
Wow - I have spent literally months trying to chase this problem down. Most recently convinced that because my Pi had no real time clock and would lose time when disconnected (often moving around and must rely on wifi only) - causing wifi to stop working (seemed to start working every time I manually changed the time). After installing a hardware RTC - still had problems. Today managed to confirm problem only appears when camera was plugged into usb 3 port, and not usb 2 port. Did a search and landed here.
D*mn ! At least I now know the problem. Kinda sucks because one or reasons for upgrading to Pi4 was the USB3. And I won't always be in 5GHz wifi zone, so guess I'm still stuck with USB2. I wonder if there is a hack for this (ie. appropriately placed tinfoil or some such) ...
My Pi4 and have same issue. As soon as I plug my ASI camera into USB3 it cause slow down or even drop connection if signal is weaker. For this reason I must put AP out of window so it have direct visibility to my Pi4 in my yard and it is working.
I use my Astroberry in hotspot mode and VNC into it. Usually everything goes fine, but tonight I couldn't get the hotspot and my devices connected to USB 3 to work.
Could you kindly explain to me how to create a hotspot that works in the 5GHz instead of 2.4?
There seems to be a problem (with Stellarmate) actually using 5 GHz WiFi. I can switch to 5 GHz in hotspot mode but when I try and change to 5 GHz for my home WiFi using network settings in VNC it doesn’t stick. It always connects to 2.4 GHz in 802.11n mode - 72 mbps is max PHY rate even when I am inside in the same room as the google wifi puck. I did switch location to US for WiFi settings.
PS in answer to the question on enable 5 GHz in hotspot mode - you do this via the Stellarmate app in the device settings section.
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